Double cantilever supported doctor blade

ABSTRACT

A DOCTOR IS DISCLOSED HAVING A PIVOTABLE DOCTOR BACK PARALLEL TO AND SPACED FROM A ROLL OF A PAPER MAKING MACHINE. A BLADE CARRIED BY A BLADE HOLDER IS CONNECTED TO THE BACK BY RESILIENT MEANS COMPRISING A FIRST CANTILEVER CONNECTED TO THE DOCTOR BACK AND PROJECTING AWAY FROM THE ROLL, AND A SECOND CANTILEVER CONNECTED TO THE FREE END OF THE FIRST CANTILEVER WITH THE FREE END OF THE SECOND CANTILEVER PROJECTING TOWARD THE ROLL. THE SECOND CANTILEVER SUPPORTS ON THE FREE END THEREOF A BLAND HOLDING ASSEMBLY TO CARRY THE BLADE. TEH BLADE IS THUS CARRIED BY A DOUBLE CANTILEVERED RESILIENT MEANS FOR SUPPLEMENTING THE RESILIENCY OF THE BLADE FOR CONTOUR FOLLOWING ENGAGEMENT OF THE BLADE WITH THE ROLL.

Feb. 23, 1971 D. 8. DE NOYER" DOUBLE CANTILEVER SUPPORTED DOCTOR BLADEFiled Dec. 19, 1968 "Q A z United States Patent Office 3,564,640 DOUBLECANTILEVER SUPPORTED DOCTOR BLADE Donald B. De Noyer, Beloit, Wis.,assignor to Allis- Chalmers Manufacturing Company, Milwaukee, Wis. FiledDec. 19, 1968, Ser. No. 785,200 Int. Cl. D21g 3/ 00, 3/02, 3/04 U.S. Cl.15-25651 2 Claims ABSTRACT OF THE DISCLOSURE A doctor is disclosedhaving a pivotable doctor back parallel to and spaced from a roll of apaper making machine. A blade carried by a blade holder is connected tothe back by resilient means comprising a first cantilever connected tothe doctor back and projecting away from the roll, and a secondcantilever connected to the free end of the first cantilever with thefree end of the second cantilever projecting toward the roll. The secondcantilever supports on the free end thereof a blade holding assembly tocarry the blade. The blade is thus carried by a double cantileveredresilient means for supplementing the resiliency of the blade forcontour following engagement of the blade with the roll.

CROSS REFERENCE TO RELATED PATENT APPLICATIONS I have copending patentapplications related to the type of apparatus disclosed herein andentitled Doctor Assembly Ser. No. 785,199 and Doctor Blade HoldingAssembly, Ser. No. 785,198 which were both filed concurrently with thisapplication.

BACKGROUND OF THE INVENTION Field of the invention This inventionrelates generally to apparatus used in paper making machines and inparticular to doctors which are used to scrape pulp and water frombreast rolls in Fourdriniers or forming cylinders in cylinder machines,wet broke and water from press rolls, and web crumbs from rolls anddrums in web drying assemblies.

Description of the prior art Arrangements for applying doctor blades tothe surfaces of rolls in paper making or calendering machinery have beendisclosed in many prior art patents beginning perhaps with U.S. Pat.242,753 of 1881. Although U.S. Pat. 2,191,366 of 1940 disclosed aflexible strip doctor blade yieldably held against a roll surface by aresilient blade holder, it remained for my own U.S. Pat. 3,3 87,317 of1968 to disclose a roll and a flexible strip doctor blade held in bladeholders for endwise insertion and removal along a path parallel to theroll, with resilient rods of substantial length connecting each bladeholder to a doctor back, so that the flexibility of the rodssupplemented the flexibility of the blade itself to provide improvedcontour following and uniform pressure characteristics of the blade onthe roll surface. As paper making machines have continued to becomelarger and wider rolls 300 to 400 inches Wide are now needed where rollsof much less width were used in the past. Continued innovation in thefield of this invention is therefore necessary in order to providesatisfactory doctoring of such wide rolls. The objects of the presentinvention such as are hereinafter set forth are directed to furtherimprovements and advances in the state of the art illustrated by theseprior art patents and in particular my own U.S. Pat. 3,387,317.

3,564,640 Patented Feb. 23, 1971 SUMMARY OF THE INVENTION An object ofthe present invention is to provide a doctor assembly with improved rollcontour following and pressurized scraping characteristics.

Another object of the present invention is to provide a doctor assemblywith an improved cantilever support for a blade holder and blade, whichwill eliminate a need for preloading blade holders in order to insertblades and eliminate a need for protective covering structure such ashas been required with certain commercially popular prior art structuresincluding my own U.S. Pat. 3,387,317 in order to prevent water or crumbstraveling over the blade holder and landing back on the roll from whichsuch water or crumbs have been removed.

Another object of the present invention is to provide a new and improveddoctor assembly in which a doctor back may be arranged in closeproximity to a roll but nevertheless provide a flexible support meansfor a blade holder of greater length than the distance between thedoctor back and the roll.

According to a preferred embodiment of the present invention a doctorblade is carried by a blade holder which is in turn connected to adoctor back by resilient means comprising a first cantilever connectedto the doctor back and projecting away from the roll, and a secondcantilever connected to the free end of the first cantilever with thefree end of the second cantilever projecting toward the roll. The secondcantilever supports on the free end thereof a blade holding assembly tocarry the blade. The blade is thus carried by a double cantileveredresilient means for supplementing the resiliency of the blade forcontour following engagement of the blade with the roll.

Other features and objects of the invention that have been attained willappear from more detail description of the invention to follow withreference to an embodiment of the present invention shown in thedrawing.

BRIEF DESCRIPTION OF THE DRAWING The accompanying drawing shows afragmentary perspective view of a paper making machine roll and doctorassembly according to the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to the drawing adoctor assembly 1 is provided with a doctor back 2 parallel to andspaced from a roll 3 of such as a paper making machine. The back 2 ismounted on means (not shown) to pivot about the axis 4. An actuatingmeans (not shown) is connected to the back to selectively rotate theback clockwise or counterclockwise as indicated by the arrows 5 and 6.

The assembly 1 is provided with a resilient blade 10 extending along theentire width of roll 3 and having a first portion 11 of the blade, i.e.,its leading edge engageable with the surface of roll 3. The blade 10 hasa second portion 12, i.e., its trailing edge, with a particular crosssectional configuration, in part thicker than the first portion 11 ofblade 10, for a purpose that will appear as this description proceeds.

A blade holder assembly 15 is provided with a width corresponding to thewidth of blade 10. The blade holder assembly 15 comprises a plurality ofsegments 16 each having an upper jaw 17 and lower jaw 18. The jaws 17and 18 define a forward facing slot 20 and rearward facing slot 21. Thelower jaw 18 is provided with an unturned lip 22 for engaging thethicker part of the trailing portion 12 of blade 10. The blade 10 isinserted into the cavity 20 by sliding the blade in slot 20 along a pathof movement parallel to the axis 4. End caps (not shown) may cover theopen ends of slot 20 and retain the blade 10 therein while the lip 22prevents the blade 10 falling out of slot 20 toward roll 3. The lip 22also limits movea 3 grient of the blade'10 relative to the blade holderassem- Resilient means 30 are provided to connect the doctor back 2 tothe blade holder assembly 15. The resilient means 30 may include a strip31 on the doctor back 2 with a first end of a mounting member 32connected to the strip 31 and doctor 2 as by screws 33. A second end ofmounting member 32 projects as a first cantilever away from the roll 3.The second end of mounting member 35 is arranged to sandwich strip 34between the second end of member 32 and the first end of member 35. Aflat strip 36 is arranged on the side of member 35 opposite to andaligned with strip 34 and screws 37 passing therethrough connecttogether the second end of mounting member 32 and the first end ofconnecting member 35 projects from strips 34, 36 in parallel spacedalignment with mounting member 32 as a cantilever toward roll 3. Thecantilever members 32, 35 may be of any length desired in order toprovide the degree of flexibility and resiliency desired regardless ofthe spacing between doctor 2 and roll 3 desired or necessitated by otherdesign or construction considerations. The connecting member 35 mayextend the entire width of the roll 3 or may be an assembly of abuttingsegments 38, 39 to provide along with blade assembly 15 and blade 10, acover over the space between doctor 2 and roll 3.

The second end of member 35, or segments 38, 39 thereof, projecting as asecond cantilever and toward roll 3, may be inserted into the rearwardfacing slot 21 defined in blade holder segments 16 and secured thereinby bolts 44. The segments 38, 39 of the connecting member 35 and thesegments 16 of the blade holder assembly 15 are arranged relative toeach other to provide for adjacent edges of segments 38, 39 beingoverlapped by a segment 16 of the blade holder assembly 15.

In the assembly and operation of the described apparatus, with theresilient means 30 attached to doctor back 2 and the blade holdersegments 16 attached to resilient means 30, the doctor back may berotated about axis 4 in the direction of arrow 5 to raise the bladeholder assembly above roll 3 for convenient insertion or removal ofblade 10. A blade 10 can be inserted endwise, that is along a path ofmotion parallel to the axis 4, into the slot without preloading theblade holder segments 16, as the overlapped and overlapping relationshipbetween the segments 38, 39 and the blade holder segments 16 willmaintain at all times the slot 20 in each holder segments 16 inalignment for insertion of a blade 10. With a blade 10 inserted in slot20, doctor back 2 may be rotated about axis 4 in the direction indicatedby arrow 6 until blade 10 contacts the surface of roll 3 with a pressuresuch as may be selected by the machine operator. With blade 10 makingpressure contact with roll 3 the double cantilevered resilient means isfree to flex and this resiliency supplements the resiliency of theblades 10 to provide for improvided performance in the blade followingthe contour of roll 3 and applying pressure uniformly thereto across theentire width of roll 3.

From the foregoing detailed description of the present invention, it hasbeen shown how the objects of the invention have been attained in apreferred manner. However, modifications and equivalents of thedisclosed concepts such as readily occur to those skilled in the art areintended to be included within the scope of this invention.

The embodiments of the invention in which an exclusive property orprivilege is claimed are defined as follows:

1. A doctor assembly for a roll in a paper making machine, the doctorassembly comprising:

(A) a doctor back adapted for mounting in parallel spaced arrangement toa paper machine roll;

(B) a resilient blade having a first portion along the entire widththereof for engagement with the surface of the roll;

(C) resilient means connecting the blades to the back;

(D) the resilient means comprising a mounting member and a flexibleconnecting member, the mounting member having a first end connected tothe doctor back and a second end projecting as a first cantilever awayfrom the roll;

(E) the flexible connecting member being spaced from and parallel to themounting member on a side of the mounting member remote from the doctorback, with a first end of the flexible connecting member being connectedto the second end of the mounting member and with a second end of theflexible connecting member projecting as a second cantilever and towardsaid roll;

(F) the second end of the flexible connecting member terminating with anedge in a vertical plane between the first end of the mounting memberand the roll, and with the second end and the terminal edge of theflexible connecting member being connected to the blade; and

(G) the flexible connecting member is an assembly of segments arrangedwith adjacent edges of adjacent segments in abutting relation and normalto a central axis through the roll with the assembly of segmentsproviding a continuous imperforate surface between the second end of themounting member and the terminal edge of the flexible connecting memberof a width corresponding to the width of the roll whereby the flexibleconnecting member and the blade connected thereto cover the spacebetween the doctor back and the roll and the blade is carried by adouble cantilever resilient means for supplementing the resiliency ofthe blade for contour following engagement of the blade with the roll.

2. An apparatus according to claim 1 in which the segments are bondedtogether along the abutting edges to provide an integral assembly ofsegments forming the flexible connecting member of a total widthcorresponding to the width of the roll.

References Cited UNITED STATES PATENTS 2,191,366 2/1940 Buccicone et al.l5256.5l

WALTER A. SCHEEL, Primary Examiner L. G. MACHLIN, Assistant Examiner

